BERLIN: The German government is considering expanding the powers of technical inspectors examining cars in the wake of the diesel emissions scandal engulfing Volkswagen, a spokesman for the Transport Ministry said on Monday.

The comments came after the head of the northern branch of Germany's Association for Technical Inspection accused Berlin of bowing to pressure from the automotive industry to prevent inspectors from checking software installed in vehicles.

Guido Rettig told Die Welt newspaper in an interview that his organisation had insisted for years that checking software should be part of the remit of technical experts, but that its efforts had been unsuccessful.

"The carmakers asserted that engine software is a company secret," he said.

"We unfortunately did not have the legal possibility to look at engine control and installed software. And so, our inspectors had no way of detecting the manipulation in the nitrogen oxide of diesel vehicles," he added.

A spokesman for the Transport Ministry said Rettig had raised a point that was already being reviewed by the government and said a committee was studying whether disclosing engine control software could be part of EU legislation.

The effectiveness of Europe's system to approve vehicles has come under scrutiny after the German carmaker disclosed in September, under U.S. pressure, that millions of diesel models contained software designed to circumvent emissions rules.

VW later admitted also to understating carbon dioxide emissions and fuel consumption data in Europe.

Critics have focused on the current system of different national bodies holding powers to approve vehicles, with calls for a single European entity.

A report published by the International Council for Clean Transportation (ICCT) on Monday proposed creating a European-wide type-approval body to cut the ties between manufacturers, national type-approval bodies and technical inspectors.

At present, manufacturers in the EU can "cherry pick" which national type-approval authority tests their vehicles, said the study which compared the EU procedure with the U.S. system.

The report called for EU authorities to carry out independent re-tests of vehicle emissions as is currently the case in the United States.

Tests should occur on in-use vehicles rather than on cars specially prepared by manufacturers for testing purposes, and should take place in "real world" conditions as well as laboratories, the ICCT said.

Last month, the European Commission proposed "real-world" testing would become operational from next year, but would only take full effect after a two-year phase-in for new vehicles from 2017.